Process for producing wool wax alcohols and fatty acids



United States Patent 3,526,647 PROCESS FOR PRODUCING WOOL WAX ALCOHOLSAND FATTY ACIDS Conrad J. Sunde, Garden City, N.Y., and Thomas B.Richey, Jr., Westfield, N.J., assignors to Malmstrom Chemical Corp.,Linden, N.J., a corporation of New Jersey No Drawing. Filed July 10,1968, Ser. No. 743,625 Int. Cl. C07c 167/42 US. Cl. 260-39725 6 ClaimsABSTRACT OF THE DISCLOSURE Wool wax alcohols and fatty acids areproduced by saponifying wool grease with caustic alkali in a co-solventmixture of isopropyl alcohol and water, followed by extraction of thewool wax alcohols from the saponified grease by subjecting thesaponified product to countercurrent extraction with heptane. Theheptane extract is washed, first with dilute KOH solution, and then withWater, using a counter-current rotary disc flow extractor. The solventis then evaporated from the purified extract to recover the wool waxalcohols. The raflinate, which contains soaps of fatty acids, alcoholand some heptane, is

. acidified and then stripped free of the solvent fraction in acontinuous stripper still to recover the fatty acid, the latter beingthen water-washed and dried.

This invention relates to the production of wool wax alcohol and woolwax fatty acids, and is more particularly concerned with the productionof these materials from wool grease.

It has heretofore been suggested to produce these alcohols and acidsfrom wool grease by saponifying the wool grease, then extracting thesaponified mass with a solvent for the unsaponifiable constituents,withdrawing the solvent layer and evaporating the solvent from theextract in order to recover the unsaponifiable material.

The procedures heretofore suggested for producing Wool Wax alcohols bysaponification of Wool grease, followed by extraction of the saponifiedmixture, must be carried out under carefully controlled conditions, inorder to avoid undesirable phase distribution and the formation ofundesirable emulsions. For these and other reasons, complete orsubstantially complete saponification of wool grease is difficult toachieve.

The principal object of the invention is to provide a process fortreating wool grease so as to separate wool wax alcohols and wool waxacids therefrom in a form as pure as possible.

Another object is to provide a process for completely saponifying woolgrease whereby to obtain therefrom an alcohol of very low saponificationvalue.

Another object of the invention is to provide a process for thecontinuous extraction and recovery of wool wax alcohols from saponifiedwool grease.

Another object of the invention is to provide a process of extractingwool wax alcohols from soaps obtained by the saponification of woolgrease.

Another object of the invention is to provide a process for the recoveryof wool grease fatty acids from the raifi nate yielded by the extractionof wool wax alcohols from saponified wool grease.

The process of the invention involves, first, the saponifi- "ice cationof the wool grease by means of alkali in the presence of a mixture ofisopropyl alcohol and Water as cosolvents; second, the extraction ofwool wax alcohol from the saponified mixture, using heptane or hexane asa solvent; and then the Washing of the heptane-wool wax alcohol extractwith a solution of potassium hydroxide, and subsequently with water, towash out the soaps that may be present therein.

It is an advantage of the process that dilution of the saponifiedproduct with a certain amount of isopropyl alcohol and water serves toprevent emulsification of the system and permit good separation ofphases during the subsequent extraction step.

In accordance with the invention, the extraction step and also, ifdesired, the washing step are best achieved in a continuouscounter-current rotary disc extraction column. The latter may take theform of the well-known Rotating Disc Column or so-called Turbo-Mixer,supplied by the Turbo-Mixer Division of General American T ransportationCorporation, New York, N.Y.

By the procedure of the invention, wool grease can be saponified in aperiod of less than 24 hours to yield an alcohol fraction having asaponification value of 2.0 or less. The extraction of the wool waxalcohols from the saponified mixture in accordance herewith by the useof heptane as solvent, may be achieved with an extraction efliciency ofusing a solventzfeed ratio of 1:1. Higher ratios of solvent relative tothe feed may be expected to result in even higher extractionefiiciencies as well as in purer products (alcohol and acids).

In carrying out the step of saponifying wool grease, either sodiumhydroxide or potassium hydroxide may be employed. We prefer, however, touse sodium hydroxide. The amount of sodium hydroxide should normallyapproximate 11 to 12% of the wool grease, by weight, charged to thesaponifying vessel. The latter is provided with suitable agitation meansto facilitate the reaction between the alkali and the fatty acids in thewool grease.

Complete saponification to the extent of at least 99% is essential inorder that the wool wax alcohol obtained shall be one having asaponification value of 2 or less. It is an advantage of the inventionthat it provides a satisfactory method for saponifying wool grease in amanner which yields an alcohol fraction having a saponification value of2 or less.

We have found that the use of isopropyl alcohol as a co-solvent withwater in the step of saponifying the Wool grease facilitatessaponification of wool grease and makes it possible to obtain 99%saponification in 24 hours at reflux temperature and atmosphericpressure. The isopropyl alcohol, moreover, also serves as a co-solventduring the subsequent steps of extracting and purifying the wool waxalcohol and wool grease fatty acid fractions.

In the operation of the saponification step, the isopropyl alcohol-waterwool grease mixture becomes one phase. Using a reasonable amount ofagitation, the saponification of even difficultly saponifiable woolgrease may be carried to 95% completion in 6 to 8 hours, and to 99%completion in 24 hours or less, at atmospheric pressure, with productionof a wool wax alcohol having a saponification value of 2 or less.

The herein described procedure utilizing isopropyl alcohol as aco-solvent with water in the saponification step makes possible theproduction of a wool wax alcohol TABLE I Treat Sapon.

mcnt value of Run Solvent Temp. time, Pressure alcohol N0. used batchhrs. used produced 1 50% E20, 40% IPA. 210 8 Atmos. 6. 7 2- 45% E20, 37%IPA. 208 21 Atmos. l. 9 3 40% E10 240 7-8 -20 2. 2 4 235% H2O-.."245-250 24 15-20 19. 6

As will be noted from Table I, the material obtained in Run #2 (21hours) exhibited a saponification value of 1.9, and the materialobtained in Run #1 (8 hours) exhibited a saponification value of 6.7;whereas those ob tained in Runs #3 and #4, wherein no isopropyl alcoholwas mixed with water, exhibited a saponification value of 2.2 in thecase of #3, where water and a treatment time of 7-8 hours was used, ascompared to a value of 19.6 in Run #4, wherein 235% water and treatmenttime of 24 hours were used. In both Run #3 and Run #4, pressureequipment is required.

The saponified wool grease is then diluted with a mixture of isopropylalcohol and water, whereby to prevent emulsification, and permit sharpseparation of phases during the subsequent extraction step. To that end,in the case of a saponified mixture made by treating 8000 pounds oflanolin with 910 pounds of sodium hydroxide, 3200 pounds of isopropylalcohol and 3440 pounds of water, was diluted with approximately 16,000pounds of isopropyl alcohol and 39,600 pounds of water. It will be seenfrom the foregoing figures that during saponification, approximately 0.4part of isopropyl alcohol and approximately 0.43 part of water are usedfor each part of lanolin, by weight, and for dilution of the saponifiedproduct, approximately 2 parts of isopropyl alcohol and approximately 5parts of water are used (for each part of lanolin, by weight).

The saponified wool grease is then treated to extract the wool waxalcohol therefrom. The extract and extracted soap (ratfinate) are thentreated to recover the wool wax alcohol and fatty acid fractions.

In accordance with the invention, the extraction of the wool waxalcohols from the soap-ispropanol-water mixture is carried oncontinuously and is effected by the use of hexane or heptane as solvent.Hexane, being a volatile, inflammable solvent, it is preferred to employthe less volatile heptane, which has been found to perform equally aswell as hexane in the extraction operation.

Preferably, the extracting operation is conducted in the well-known typeof rotating disc contactor type of countercurrent extractor columns(referred to herein as the R.D.C. unit). This form of extraction columnconsists, in brief, of a number of compartments formed by a series ofstator rings, with a rotating disc centered in each compartment andsupported by a rotating shaft. (Chemical Engineering Progress, vol. 51,No. 3, March 1955, p. 14.)

In the operation of the R.D.C. unit for the extraction of wool waxalcohol from the saponified wool grease mixture, the heptane isintroduced at the bottom of the column and functions as the homogeneousor complete phase. It flows upward, therein, counter-currently to thedescending saponified mixture, which enters the column at the top. Thesaponified mixture of soaps, water, and isopropyl alcohol is dispersedby the discs into the form of many small droplets (hence referred to asthe discontinuous phase), the size of the droplets depending upon thespeed of the rotor, which largely governs the extraction conditions.

The saponified material fed to the R.D.C. unit should be sutficientlydiluted with isopropyl alcohol and Water solution to ensure andfacilitate separation of the phases in the extraction operation. Theconcentration of isopropyl alcohol in the mixture of soap, water andisopropyl alcohol which is fed to the extraction column should be highenough to reduce the build-up of solids in the extraction column to aminimum.

In a specific illustration of the extraction step, the solvent (e.g.,heptane) was fed to the R.D.C. unit in a ratio of 1:1 relative to thefeed of the solution of soaps, water, and isopropyl alcohol thereto, forextracting the wool wax alcohol from the soap, isopropanol, watermixture, This amounts to a ratio of about 5:1 solvent (heptane) relativeto wool wax alcohols extracted, in contrast to ratios of the order of :1in the case of procedures heretofore employed, using batch extractionprocedure.

The temperature of both the aqueous feed and of the solvent ismaintained at approximately to F. The temperature in the extractingcolumn is maintained at 100 F. or somewhat higher to assist inminimizing the build-up of solids in the column. The rotor speed of thediscs may be maintained at 30 to 60 rpm.

The procedure hereinabove described has been found to enable extractionof wool wax alcohols from the saponified wool grease to be effected atextraction efficiencies averaging 95% or better. Extraction efliciencyis determined by extracting the extracted raflinate, and measuring theamount of extractable material not extracted by the actual extractionstep. Extraction efliciencies obtained by the herein describedprocedure, calculated from actual runs, vary from a minimum of about86.4% to as high as 97.7%.

The extract, composed of solvent (heptane) and wool wax alcohol, isdischarged at the top of the column of the R.D.C. unit, and is washed,for the removal of soaps, from which fatty acids may be recovered ashereinafter set forth. For the washing of the extract, the latter isdelivered to an R.D.C. unit, wherein the washing may be effected bysubjecting the extract to counter-current contact first with diluteaqueous solution of potassium hydroxide (desirably a 1% KOH-watersolution) followed by washing with water to wash out the KOH.

This Washing of the extract with aqueous alkali may be effected byfeeding the KOH water solution to the R.D.C. extracting column at a rateof A to the rate of feed of the extract thereto; the rotor speed beingof the order of 50-60 rpm.

The effect of this washing treatment of the extract is indicated by thefollowing data of the ash content of unwashed and washed extract:

Percent ash Unwashed extract 0.81 1400 g. extract washed with 200 ml. 1%KOH (then with 1000 ml. 5050 IPA and water) 0.02

The washing of the extract with water, following the Wash with alkali,has the further function and advantage of removing isopropyl alcoholfrom the extract. This is The quality of the wool wax alcohols obtainedby the practice of the invention is indicated by the data in Table II,showing the results of tests on such wool wax alcohols:

TABLE II Water absorption 1300 M.P. C.) 50-50 Saponification value 6.0Hydroxyl value 160 Cholesterol (percent) 31.8 Color (30% CCl Absorptionon a DU24000 spectrophotometer:

Abs. at 470 .39

Abs. at 520 0.137 Ash (percent) 0.7

The raflinate, i.e., the solution extracted soapawater isopropylalcohol, that is separated from the wool wax alcohol fraction in theextraction step, is composed mainly of soaps of fatty acids, and someunsaponifiables. It also contains some 4% to heptane and 7-15% isopropylalcohol. The washes from the alkali and water washing of the heptaneextract of the saponified wool grease are desirably combined with theraffinate.

To recover solvent and fatty acids present in the raffinate, the latteris acidified, as with dilute sulphuric acid, to yield the fatty acids ofthe soaps present in the raffinate. The mixture of fatty acids andsolvents is pumped through a continuous stripper column to recover thesolvents (heptane and isopropyl alcohol) and completely remove them fromthe raflinate.

Acidification of the rafiinate should be such as to bring the pH thereofto well below 7.0; otherwise a considerable amount of foaming will occurduring the operation of the stripper column for removal of the solvents.The use of a continuous stripper column for recovery of the solvents hasthe further advantage of contributing to the production of fatty acidsof good color, by reason of the low time of contact that prevails duringthe recovery of the solvents. The stripper column employed mayconveniently take the form of the well-known Rodney-Hunt unit.

After removal of the solvents, the fatty acids are decaned, water washedand dried.

The properties of the fatty acids recovered from the rafiinate by theherein described procedure are indicated by the following data:

TABLE III Acid value 149.0 15% Union Colorimeter color 3.4-4Saponification value 170.5 Hydroxyl value 58.2 Unsaponifiable (percent)7.4 Iodine value 10.6 Flash point F.) 410 6 1y 180 and an unsaponifiablecontent of approximately 2.6.

Although the unsaponifiable value of 7.4% in Table III indicates thatsome wool wax alcohol remained unextracted and was present in therafiinate, this figure is consistent with the figures above set forthfor extraction efficiencies obtainable in the practice of the invention.The use of additional amounts, i.e., a higher ratio, of solvent in theextraction step would serve to reduce substantially the amount ofunsaponifiables present in the fatty acid fraction.

What is claimed is:

1. The process of producing wool wax alcohols and acids from woolgrease, which comprises saponifying the wool grease in the presence of aco-solvent mixture of isopropyl alcohol and water, and subjecting thesaponified wool grease to continuous counter-current extraction in arotating disc extraction column with a hydrocarbon solvent selected fromthe group consisting of hexane and heptane, subjecting the solventextract to continuous coun ter-current washing first with dilute aqueousalkali solution and subsequently with water, and evaporating saidsolvent from the washed extract to recover the wool Wax alcoholstherefrom.

2. The process as defined in claim 1, wherein the solvent from which thewool wax alcohols are recovered is delivered to and utilized as solventin said extraction step.

3. The process of producing wool wax alcohols which comprisessaponifying wool grease in a co-solvent solution of isopropanol andwater, treating the saponified mass with a solvent selected from thegroup consisting of hexane and heptane in counter-current continuouscontact in a rotating disc extraction column to extract the wool waxalcohol from said mass, and washing soapy materials from said extract bysubjecting the same to continuous countercurrent contact with diluteaqueous solution af alkali.

4. The process as defined in claim 3, wherein fatty acids are recoveredfrom said combined rafiinate and soapy material washed from saidextract.

5. The process of producing wool wax alcohols which comprisessaponifying wool grease in a co-solvent mixture composed of isopropylalcohol and water, subjecting the saponified mass to continuouscounter-current extraction is a rotating disc extraction column withheptane to separate the wool wax alcohol fraction from the saponifiedmass, subjecting the extract of the heptane-wool wax alcohol tocontinuous counter-current washing with dilute alkali solution and withwater, and evaporating the heptane from the washed extract fraction torecover the wool Wax alcohol.

6. The process as defined in claim 5, wherein the raffinate obtained insaid extraction of said saponified mass with heptane is acidified withmineral acid and subjected to continuous stripping action for removal ofsolvent and recovery of fatty acids therefrom.

References Cited UNITED STATES PATENTS 2,508,220 5/1950 Buxton 260397.252,866,781 12/1958 Chase et al 260-39725 2,905,677 9/1959 Fevig et al.260-397.25

ELBERT L. ROBERTS, Primary Examiner

